US3891760A - Nematicidal compositions comprising 2-chloro-6-methoxy-4-(trichloromethyl)-pyridine and 2,2-dimethyl-2,3-dihydrobenzofuranyl-7-N-methyl carbamate - Google Patents

Abstract

Pesticidal compositions containing a mixture of 2-chloro-6methoxy-4-(trichloromethyl)-pyridine and 2,2-dimethyl-2,3dihydrobenzofuranyl-7-N-methyl carbamate are disclosed. Such composotions are useful in the treating and disinfection of soil infested with nematodes, it having been found that the toxic ingredients of said compositions are mutually activating.

Description

United States Patent 11 1 OMelia NEMATICIDAL COMPOSITIONS COMPRISING 2-CHLORO-6-METHOXY-4-(TRI- CHLOROMETI-IYL)-PYRIDINE AND 2,2-DlMETHYL-2,3- DIHYDROBENZOFURANYL-7-N-METHYL CARBAMATE I [75] Inventor: Frances C. OMelia, Pleasant Hill,

Calif.

[73] Assignee: The Dow Chemical Company,

Midland, Mich.

221 Filed: Mar. 25, 1974 1211 Appl. No: 454,204

[52] US. Cl 424/263; 424/285 [5i] Int. Cl. AOln 9/20; AOln 9/22 [58] Field of Search 424/263, 285

[ June 24, 1975 [56] References Cited UNITED STATES PATENTS 3.244.722 4/1966 Johnson et al 424/263 X 3.474.171 10/1969 Scharpf 424/285 Primary Examiner-Albert T. Meyers Assistant E,\'aminer-Leonard Schenkman Attorney, Agent, or FirmS. Preston Jones 5 7 ABSTRACT 6 Claims, N0 Drawings NEMATICIDAL COMPOSITIONS COMPRISING 2-CHLORO-6-METHOXY-4-(TRICHLOROME- THYL)-PYRIDINE AND 2,2-DIMETHYL-2,3-DIl-IYDROBENZOFURANYL-7- N-METHYL CARBAMATE BACKGROUND OF THE INVENTION It is an object of this invention to provide new ncmaticidal compositions which are useful in the control in soil of nematodes and other invertebrate organisms which attack plant roots. A further object is to supply a new agronomic practice for improving the plant growing properties of soil and the ability of soil to support the growth of crops. An additional object is the provision of a new method and composition for treating soil to obtain improved controls of soil-dwelling invertebrate organisms such as nematodes.

PRIOR ART The 2-chloro-6-methoxy-4-(trichloromethyl)- pyridine employed in accordance with the teachings of the present invention is a light yellow non-viscous liquid having a boiling point of 130C. at 2 millimeters of mercury and a vapor pressure of 6.5 X mm at 25C. and which has very low water solubility and is soluble in many common organic solvents. The compound is taught in U.S. Pat. No. 3,244,722 and can be prepared by reacting 2,6-dichloro-4-(trichloromethyl)- pyridine with sodium metal and methanol at reflux temperature for from about 2-15 hours with production of the desired 2-chloro-6-methoxy-4-(trichloromethyl)- pyridine. The product is removed by distilling off the solvent, extraction with a solvent, filtering off the byproducts, removing the solvent and recovering the product as a residue.

The 2,2-dimethyl-2,3-dihydrobenzofuranyl-7-N- methyl carbamate employed in accordance with the teachings of the present invention is a white solid melting at l50l52C. The compound is taught in U.S. Pat. No. 3,474,171 and can be prepared by reacting 7- hydroxy-2,2-dimethyl-2,3-dihydrobenzofuran in ether with methyl isocyanate in triethylamine at room temperature. The solid product which precipitates is separated and, if desired, the product can be purified by recrystallization from methylcyclohexane.

SUMMARY OF THE INVENTION The new nematocidal compositions of the present invention comprise about 1 part by weight of 2-chloro-6- methoxy-4-(trichloromethyl)pyridine in admixture with from about 1/32 to about 16 parts by weight of 2,- 2-dimethyl-2,3dihydrobenzofuranyl-7-N-methyl carbamate. This composition conveniently adapts itself to the treatment of soil or other growth media to improve the ability of the soil to support plant growth and to benefit the plants grown in the treated soil. Such practice protects the plants from the ravages of soildwelling invertebrate organisms which attack their roots and improves the growth and harvest of crop plants. It has also been found that the treatment accomplishes changes in the soil which stimulate the growth and improve the growth characteristics of crops grown therein. It is among the advantages of the present invention that the toxicants in the mixture appear to be mutually activating so that a greater than additive or synergistic result is accomplished as regards the effect on the plant growing properties of the soil and the control of undesirable organisms and particularly invertebrates such as nematodes.

The composition comprising the mixture of toxicants is sufficiently increased in effectiveness so as to permit the effective utilization of reduced amounts of the 2- chloro-6-methoxy-4-(trichloromethyl)pyridine and of 2,2-dimethyl-2,3-dihydrobenzofuranyl-7-N-methyl carbamate. The crop yields and the control of soil dwelling organisms obtained are much superior to those obtained when either of the constituents of the mixture is employed alone. An additional advantage is that these reduced effective dosages of the mixture of toxicants materially reduce the hazards of soil residues. Thus, the practice of the present invention provides a very desirable economic advantage for the agriculturalist.

2-Chloro-6-methoxy-4-(trichloromethyl)-pyridine is a mobile liquid, and 2,2-dimethyl-2,3- dihydrobenzofuranyl-7-N-methyl carbamate is a crystalline solid. Mixtures of the compounds are somewhat soluble in many organic solvents and of low solubility in water. They are adapted to be readily and conveniently distributed in soil. Further, when so employed, the compounds accomplish a substantially complete kill of nematodes, and induce soil changes which improve the ability of the soil to support plant growth and the growth characteristics of crops raised on the treated soil. It is among the advantages of the present invention that mixtures of these compounds, while sufficiently persistent to accomplish the desired effect upon the soil and upon soil-inhabiting organisms, dissipate in a reasonable period of time.

The distribution of at least a minimum effective dosage of the mixture of 2-chloro-6-methoxy-4-(trichloromethyl)pyridine and 2,2-dimethyl-2,3- dihydrobenzofuranyl-7-N-methyl carbamate in soil is essential and critical for the practice of the present invention. In general, good improvement in the ability of the soil to support plant growth and good controls of nematodes and other root attacking invertebrate organisms are obtained when said mixed compounds are distributed in soil in an amount of at least about 0.25 part by weight of the mixed compounds per million parts by weight of the soil. A good working range is from about 0.25 to about 600 parts by weight of the mixed compounds per million parts by weight of the soil.

In general field applications, it is usually preferred that the compounds be distributed in the soil to a depth of from 3 to 12 inches at rates of from about 0.013 to about 20 pounds per treated acre [1 pound distribution through 3 inches of soil is approximately 1 part of the active compound mixture per million parts of soil (ppm)]. Oftentimes it is desirable to distribute the compounds to a depth of as much as 48 inches at rates of as much as 48 pounds per treated acre to avoid reinfestation of the soil by deep dwelling nematodes which cause plant disease. Rates as low as 0.25 pound per overall acre may be employed in row or band applications where the treated band in which the crop is seeded or transplanted occupies as little as one-eighth of the overall area on which the crop is being grown.

When compositions embodying a liquid or solid carrier are used, as hereinafter described, the amount of the composition is adjusted to distribute substantially the above described amounts of the active toxicant mixture per acre.

In one embodiment of the invention, the treated soil is planted with the desired crop plant following the distribution of the toxicant compounds in the soil. Where minimum dosages of the toxicant compounds are distributed in soil, the treated soil may be immediately planted with the desired crop. Following the distribution of large dosages of the toxicant compounds, it is desirable that any planting operation not be carried out for a period of from several hours to several days, the exact period depending upon the concentration of the toxicant compounds in the soil and the resistance of the species concerned to the compounds. Where the mixture of toxicant compounds is employed for the treatment of the soil adjacent to the root system of established plants having resistance to the compounds and in side dressing operations, the existing vegetation is not unfavorably effected by minimum effective concentrations of the toxicant compounds temporarily present in the soil.

In carrying out the improved agronomic practice of the invention, the 2-chloro-6-methoxy4-(trichloromethyl)pyridine and 2,2-dimethyl-2,3- dihydrobenzofuranyl-7-N-methyl carbamate may be mixed or ground together and the resulting product employed directly for the treatment of soil. However, the present method also embraces the employment of a liquid or dust composition wherein the mixed active compounds are applied to the soil in admixture with an inert adjuvant as a carrier. In such usage, the active compounds may be modified with one or a plurality of additaments or soil treating or parasiticide adjuvants, including water or other liquid carriers, surface active dispersing agents and finely divided inert solids. Depending on the concentration of toxicant compounds, such augmented compositions are adapted to be distributed in soil, or employed as concentrates and subsequently diluted with additional inert carrier to produce the ultimate treating compositions.

Liquid compositions containing the 2-chloro-6- methoxy-4-(trichloromethyl)pyridine and 2,2- dihydrobenzofuranyl-7-N-methyl carbamate in the desired amounts may be prepared by dissolving the compounds in a liquid organic carrier at ordinary temperatures. Suitable liquid organic carriers include liquid aliphatic and aromatic compounds such as acetone, toluene, xylenes, naphthas and hydrocarbon mixtures derived by the distillation of petroleum or coal. Depending on the concentration of the mixture of toxicants, such augmented compositions are adapted to be distributed in the soil or otherwise employed as concentrates and subsequently diluted with additional carrier to produce the ultimate treating compositions. Aqueous liquid compositions containing the desired amount of the mixture of toxicants in water can be prepared by dispersion the toxicants in water with the aid of a suitable surface active dispersing agent such as an ionic or non-ionic emulsifying agent. Such compositions may contain one or more water immiscible solvents for the mixture of toxicants, and in such compositions the carrier comprises an aqueous emulsion, i.e., a mixture of water immiscible solvent, emulsifying agent and water. Dispersing and emulsifying agents which can be employed in the compositions include the condensation products of alkylene oxides with phenols and organic acids, alkyl aryl sulfonates, polyoxyethylene derivatives of sorbitan esters, complex ether alcohols, mahogany soaps and the like. In another method, aqueous liquid compositions containing the mixture of toxicants can be prepared by dissolving said toxicants in a water miscible solvent such as acetone or methyl ethyl ketone and then diluting said solution with water to produce the ultimate treating compositions. These compositions may also include an ionic or non-ionic emulsifying agent, if desired.

In the preparation of dust compositions, the 2- chloro-6-methoxy-4-(trichloromethyl)pyridine and 2,- 2-dimethyl-2,3-dihydrobenzofuranyl-7-N-methyl carbamate are dispersed in and on a finely divided inert solid such as talc, chalk, gypsum and the like. In such operations, the carrier is mechanically ground with the compound or wet with a volatile organic solvent solution thereof. Similarly, dust compositions containing the mixture of toxicants can be prepared from various of the solid, surface active dispersing agents, such as bentonite, fullers earth, attapulgite and other clays. Depending on the proportions of ingredients, these dust compositions may be employed as concentrates and subsequently diluted with additional solid surface active dispersing agent or with talc, chalk or gypsum and the like to obtain the desired amount of the active compounds in a composition adapted to be employed for the treatment of soil. Also, such concentrate dust compositions may be dispersed in water with or without the aid of a dispersing agent to form aqueous soil treating compositions.

In formulating the compositions, it is essential to maintain the proportions of from about 1 part by weight of 2-chloro-6-methoxy-4-(trichloromethyl)pyridine to from 1/32 to 16 parts by weight of 2,2-dimethyl- 2,3-dihydrobenzofuranyl-7-N-methyl carbamate and to provide an effective amount of said mixture in the finished composition in order to maintain the desired synergistic effect. The concentration of the mixture of toxicants in liquid compositions employed to supply the desired dosage generally is from about 0.00001 to 50 percent by weight, although compositions employing as high as percent may be employed. In dusts, the concentration of the mixture of toxicants may be from about 0.08 to 20 percent by weight. In compositions to be employed as concentrations, the mixture of toxicants may be present in a concentration of from about 5 to percent by weight.

When operating in accordance with the present invention, the composition can be employed as an at-planting-time-treatment such as, for example, during transplant operations or the soil may be impregnated with the mixture of toxicant compounds, or a composition containing the toxicants, in any convenient fashion, e.g., by simple mixing with the soil, by applying to the surface of soil and thereafter dragging or disking into the soil to the desired depth, or by employing water to accomplish the penetration and impregnation. In apreferred procedure, the impregnation is carried out with the water employed to irrigate the soil.

The expressions growth media or soil are employed in the present specification and claims in their broadest sense to be inclusive of all conventional soils," as defined in Websters New International Dictionary, Second Edition, Unabridged, published in 1937 by G. and C. Merriam Company, Springfield, Massachusetts. Thus, the terms refer to any substances or media in which vegetation may take root and grow, and are intended to include not only earth but compost,

manure, muck, humus, and sand and the like, adapted Grardling sfytelrln 0. a s "/1 Control over to support plant growth. Comm! Plums Ungalled roots 0 100 Very lightly galled DESCRIPTION OF THE PREFERRED 2 90-95 Lightly galled roots 3-6 75-89 EMBODIMENTS Light-medium galled roots 7-15 5074 Medium galled roots 16-20 30-49 The following examples illustrate the present inven- Medium-heavy called 7 tion and the manner by which it can be practiced but, 22:3 gang; mots 5:228 as such, should not be construed as limitations upon the Very heavily grilled overall scope of the same.

Table l Run Chemical Amount Chemical Amount Ratios Expected Actual Percent No. (2) in Pounds (3) in Pounds of Control Control Increase l J Per Acre Per Acre Chemicals in in over AzB Percent Percent Expected Control l 0 Z A 0.5 3 A 1.0 0 4 A 2.0 o 5 A 4.0 0 6 A 8.0 38 7 B 0.l3 0 8 B 0.25 0 9 B 0.5 0 {(1) 3 L0 Z5 2.0 75 12 A 0.5 B 0.5 l:l 0 l00 (6) [3 A 1.0 B 0.l3 7.7:] 0 25 100 (6) l4 A 2.0 B 0.5 4:] 0 38 100 (6) l5 A 4.0 B 0.13 31:] 0 25 100 (6) [6 A 4.0 B 0.25 l6:l 0 25 100 (6) I? A 4.0 B 0.5 iizl 0 63 100 (6) [8 A 4.0 B 1.0 4: l 25 75 200 19 A 4.0 B 2.0 2:] 75 83 ll 20 A 8.0 B 1.0 8:1 535 83 (1) Run Nos. 1-11 are control runs with Run No, I being a no chemical control (acetone-water).

(2) Chemical A represents 2-chloro-(w-mcthoxy-4-(trichloromethyl)pyridinc. (3) Chemical B represents 2,Z-dimcthyll.3-dihydrohenzoluranyl-7-N-methyl carbamatc. (4) Expected control equals /r control by chemical A '/I control by chemical B minus 71 control by chemical A X 91 control chemical 5/100 (5) "/1 increase over expected control equals actual control/expected control X 100-100 (6) "/1 increase too great to be computed EXAMPLE I Four-ounce jars were filled with 1 inch of vermiculite and thereafter to the top with moist sandy loam soil, naturally infested with root-knot nematodes The soil was compacted to a depth of within one-half inch from the top of the jar. Predetermined amounts of aqueous acetone solutions containing the compounds 2-chloro- 6-methoxy-4-(trichloromethyl)-pyridine and 2,2- dimethyl-Z,3-dihydrobenzofuranyl-7-N-methyl carbamate prepared by dissolving predetermined amounts of the one of the compounds in a predetermined amount of acetone-water were drenched onto the soil and Teflon lined screw lids were attached to the jars.

At the same time, additional soil-filled jars were treated with acetone-water alone to serve as controls. The jars were incubated at 75F. for one week and thereafter the lids removed and 5 cucumber seeds placed on the soil surface and covered with a sand cup. The jars were placed in a greenhouse under conditions conducive to good plant growth for 3 weeks. At the end of this period, the plants were removed and the roots washed free of soil and examined and graded for incidence of nematode galling according to the following grading system:

EXAMPLE ll Four-ounce jars were filled with 1 inch of vermiculite and thereafter to the top with moist sandy loam soil, heavily infested naturally with root-knot nematodes. The soil was compacted to a depth of within one-half inch from the top of the jar. Predetermined amounts of acetone solutions containing the compounds 2-chloro- 6-methoxy-4-(trichloromethyl)pyridine and 2,2- dimethyl-Z,3-dihydrobenzofuranyl-7-N-methyl carbamate prepared by dissolving predetermined amounts of one of the compounds in a predetermined amount of aqueous acetone, were drenched onto the soil and Teflon lined screw lids were attached to the jars. At the same time, additional soil-filled jars were treated with aqueous acetone alone to serve as controls. The jars were incubated at 6575F. for one week and thereafter the lids were removed and 5 tomato seeds were placed on the soil surface and covered with a sand cap. The jars were placed in a greenhouse under conditions conducive to good plant growth for 3 weeks. At the end of this period, the plants were removed and the roots washed free of soil and examined and graded for incidence of nematode galling by the system set forth hereinabove in Example I. The results of this examination,

the ratios and amounts of the chemicals employed are set forth below in Table 11.

3. The composition as defined in claim 2 wherein the composition is present as an aqueous dispersion and Table 11 Run Chemical Amount Chemical Amount Ratios Expected Actual Percent No. (2) in Pounds (3) in Pounds of Control Control Increase 1 Per Acre Per Acre Chemicals in in over A:B Percent Percent Expected (4) Control l 2 A 0.13 0 3 A 0.25 0 4 A 0.5 0 5 A 1.0 25 6 A 4.0 25 7 B 0.13 0 8 B 0.25 0 9 B 0.5 0 l1) B 2.0 25 l 1 B 4.0 45 12 A 0.13 B 0.25 1:2 0 38 100 (6) 13 A 0.25 B 0.5 1:2 0 38 100 (6) 14 A 0.25 B 4.0 1:16 45 63 40 15 A 0.5 B 0.13 4:1 0 100 (6) 16 A 0.5 B 0.5 1:1 0 25 100 (6) 17 A 1.0 B 4.0 1:4 59 95 61 18 A 4.0 B 0.25 16:1 25 63 152 19 A 4.0 B 2.0 2:1 44 70 59 20 A 4.0 B 4.0 1:1 59 88 4) (1) Run Nos. l-ll are control runs with Run No. l being a no chemical control (acetone-water).

(2) Chemical A represents 2-ch1oro-6-methoxy-4-ltrichloromethyl)pyridine.

(3) Chemical B represents 2.2-dimethyl-2 3-dihydrohcnzofuranyl-7-N-methyl carbamale. (4) Expected control equals /1 control by chemical A '/1 control by chemical B minus /r control by chemical A X '/1 control chemical 13/100 (5) I: increase over expected control equals actual control/expected control 100-100 to) '/1 increase too great to be computed Data from Tables 1 and I1 illustrate that better nematode control was obtained employing the two toxicants together than would be expected from the results obtained from employing each of the two toxicants alone. These data are obtained according to the technique described in Colby, Calculating Synergistic and Antagonistic Responses of Herbicide Combinations, Weeds, Vol. 15 (1967) pages 20-22 and Colby, Greenhouse Evaluation of Herbicide Combinations Proc. NEWCC, No. 19, pages 312-320.

What is claimed is:

l. A synergistic nematicidal composition for use in soil which comprises an inert carrier and a mixture of toxicants consisting of about 1 part by weight of 2- ch1oro-6-methoxy-4-(trichloromethyl)pyridine and from about 1/32 to about 16 parts by weight of 2,2 dimethyl-Z,3-dihydrobenzofurany1-7-N-methy1 carbamate, said mixture being present in an amount of from about 0.00001 to 90 percent by weight of the total composition.

2. The composition as defined in claim 1 wherein the carrier is an inert liquid organic carrier.

the mixture of toxicants is present in an amount of from about 0.00001 to 50 percent by weight of the total composition.

4. A method for killing nematodes in soil which comprises applying to said soil an active toxicant mixture in an amount of from about 0.013 to about 20 pounds of said active toxicant mixture per acre of the soil, said active toxicant mixture comprising about 1 part by weight of 2-chloro-6-methoxy-4-(trichloromethyl)-pyridine and from about 1/32 to about 16 parts by weight of 2,2- dimethyl-2,3-dihydrobenzofuranyl-7-N-methy1 carbamate.

5. The method as defined in claim 4 wherein said soil is impregnated with an aqueous dispersion of said active toxicant mixture and wherein the active toxicant mixture is present in an amount of from about 0.00001 to 50 percent by weight of the aqueous dispersion.

6. The method as defined in claim 4 wherein said toxicant mixture is applied in an amount of from about 0.25 to about 20 pounds per acre.

Claims (6)

1. A SYNERGISTIC NEMATICIDAL COMPOSITION FOR USE IN SOIL WHICH COMPRISES AN INERT CARRIER AND A MIXTURE OF TOXICANTS CONSISTING OF ABOUT 1 PART BY WEIGHT OF 2-CHLORO-6-METHOXY-4(TRICHLOROMETHYL)PYRIDINE AND FROM ABOUT 1/32 TO ABOUT 16 PARTS BY WEIGHT OF 2,2-DIMETHYL-2,3-DIHYDROBENZOFURANYL-7NN-METHYL CARBAMATE, SAID MIXTURE BEING PRESENT IN AN AMOUNT OF FROM ABOUT 0.00001 TO 90 PERCENT BY WEIGHT OF THE TOTAL COMPOSITION.

2. The composition as defined in claim 1 wherein the carrier is an inert liquid organic carrier.

3. The composition as defined in claim 2 wherein the composition is present as an aqueous dispersion and the mixture of toxicants is present in an amount of from about 0.00001 to 50 percent by weight of the total composition.

4. A method for killing nematodes in soil which comprises applying to said soil an active toxicaNt mixture in an amount of from about 0.013 to about 20 pounds of said active toxicant mixture per acre of the soil, said active toxicant mixture comprising about 1 part by weight of 2-chloro-6-methoxy-4-(trichloromethyl)-pyridine and from about 1/32 to about 16 parts by weight of 2,2-dimethyl-2,3-dihydrobenzofuranyl-7-N-methyl carbamate.

5. The method as defined in claim 4 wherein said soil is impregnated with an aqueous dispersion of said active toxicant mixture and wherein the active toxicant mixture is present in an amount of from about 0.00001 to 50 percent by weight of the aqueous dispersion.

6. The method as defined in claim 4 wherein said toxicant mixture is applied in an amount of from about 0.25 to about 20 pounds per acre.